Adrenocorticotropin independent macronodular adrenocortical hyperplasia (AIMAH) is considered a rare form of macronodular adrenal hyperplasia. It is an uncommon cause of primary adrenal hypercortisolism.

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Clinical presentation

Patients with AIMAH tend to present 10 years earlier on average than the time of presentation of classic Cushing disease. The age of presentation usually ranges around 40-50 years. Their symptoms also tend to be milder than that of typical Cushing disease.

Pathology

While the exact pathology is obscure, it is generally thought to result from aberrant hormone receptor signalling.

Radiographic features

CT

CT often characteristically shows massively enlarged multinodular adrenal glands. The nodules tend to vary in size ranging between 1 and 5.5 cm and are generally hypo-attenuating 3. There is also often distortion of the adrenal contour.

MRI

Signal characteristics of the glands as well as the nodules tend to be 2-3

T1: generally hypointense compared with the liver

T2: hyperintense compared with the liver

in-out phase imaging: nodules usually lose signal on out of phase imaging due to chemical shift from high intrinsic lipid content